I've never really seen a FIRE engine that doesn't use coilpacks, so i'm not sure how involved it would be to swap over.
On the FIRE engines that use coilpacks, there is an ECU to fire them. The ECU has various sensors that it uses to decide on timing. These include the lambda sensor in the exhaust, the map sensor (monitors the inlet manifold pressure), water temperature (sensor is located in the inletmanifold water way), inlet air temperature (located inside the the top of the SPI unit), and finally the TDC sensor. This takes a reading off the crank pulley (that drives the alternator belt), so that the engine knows when it is at TDC.
I'm not sure which sensors it'd need to do the timing only, as they normal handle the fueling as well.
I'm also not sure if you could just use the coilpacks and then get a standalone system to fire them, i see no reason why that wouldn't work.
Might be better off waiting for someone of the uno guys to come along, they know their Unos better than i do. I'm a Cinquecento/Seicento person!